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Franck Pachot

Franck Pachot

DynamoDB / Aurora: sparse and partial indexes

By | AWS, Cloud | No Comments

By Franck Pachot . In a previous post I tried to build a glossary about Amazon DynamoDB terms that look like relational database terms, but with a different technical meaning. Here is more about it. If you work with AWS Databases and frequently switch between DynamoDB and Aurora, or other RDS databases, you may be confused by the same terms used for different meanings. An index is a redundant structure that is maintained by the…

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Franck Pachot

K8s on Windows/VirtualBox

By | Kubernetes, Postgres | No Comments

By Franck Pachot . This is a little demo, easy to copy-paste, if you want to play with Kubernetes on your laptop. And, not a simple “Hello World” but a real database running here, able to scale up and down with full availability. Install Virtualbox I use Oracle VirtuaBox because I’m a big fan of Oracle products, especially when they are good and free. However, you can use Hyper-V (then just skip this paragraph and…

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Franck Pachot

Some Artificial Intuition in Oracle SQL_ID?

By | Oracle | One Comment

By Franck Pachot . This post is something I discovered by chance when writing about tagging SQL statement with recognizable comments. We know that Oracle is introducing more and more artificial intelligence and machine learning in the database engine, but here is the first time I see something where random or hash values seems to bring some meaning. There are two common ways to run a query and find it in V$SQL: add some tag…

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Franck Pachot

Should CPU-intensive logic be done in the DB or in application server?

By | Cloud, Postgres | No Comments

By Franck Pachot . Should CPU-intensive logic be done in the DB or in application server? Here was a answer found in Reddit: Comment from discussion xpiv’s comment from discussion "Should CPU-intensive logic be done in the DB or in application server?". Reducing the CPU usage on the database server is a major cost saver with commercial databases, like Oracle Enterprise Edition where you pay license per core. But even in Open Source, on-premises or…

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Franck Pachot

ORA-32635: not a single cell reference predicate

By | Database Administration & Monitoring | No Comments

By Franck Pachot . I spent 30 minutes to try to understand this error with a query that I’ve run in many environments for years. So if you google it you may arrive here and the solution may be checking whether you have NLS_COMP=LINGUISTIC SQL> alter session set nls_comp=linguistic; Session altered. SQL> alter session set nls_language=french; Session modifiee. SQL> select * from ( 2 select 42 snap_id,’TM’ type,’DB time’ name,0 microseconds from dual 3 )…

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Franck Pachot

Foreign Keys in MySQL, SQL, NoSQL, NewSQL

By | MySQL, Oracle, Postgres | No Comments

By Franck Pachot . In the NoSQL times, it was common to hear thinks like “SQL is bad”, “joins are bad”, “foreign keys are bad”. Just because people didn’t know how to use them, or they were running on a database system with a poor implementation of it. MySQL was very popular because easy to install, but lacking on many optimization features that you find in other open source or commercial databases. Sometimes, I even…

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Franck Pachot

Oracle – testing resource manager plans?

By | Database Administration & Monitoring, Oracle | No Comments

By Franck Pachot . I never remember that in order to use instance caging you need to set a Resource Manager Plan but don’t need to set CPU_COUNT explicitly (was it the case in previous versions?). Here is how to test it quickly in a lab. SQL> startup force ORACLE instance started. SQL> show spparameter resource_manager_plan SID NAME TYPE VALUE ——– —————————– ———– —————————- * resource_manager_plan string SQL> show spparameter cpu_count SID NAME TYPE VALUE…

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Franck Pachot

A VPC is a private cloud in a public cloud

By | AWS | No Comments

By Franck Pachot . If you are surprised that the first thing you do in a Public Cloud is creating a Virtual Private Cloud, this post is for you. This is a beginner level post. And if you are at that level, interested by what is the Cloud and what is AWS, I recommend our free AWS Discovery Days – I give it next week in French: https://www.dbi-services.com/fr/trainings/aws-discovery-days/ Today, with the “digitalization” trend, people are…

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Franck Pachot

Linux perf-top basics: understand the %

By | Cloud | No Comments

By Franck Pachot . Linux kernel has a powerful instrumentation that can be accessed easily. When you want to drill down into your program functions to understand their CPU usage, “perf” is the easiest. It can attach to the processes, sample the CPU cycles, get the symbol name, or even the call stack. And display an histogram of sample counts. This provides an easy profiling tool to understand in which function your program spends its…

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Franck Pachot

AWS: PostgreSQL on Graviton2 with newer GCC

By | AWS, Postgres | No Comments

By Franck Pachot . In the previous post I have run PostgreSQL on AWS m6gd.2xlarge (ARM Graviton2 processor). I didn’t precise the compilation option and this post will give more details following this feedback: @FranckPachot thanks for sharing the results. Our own testing showed similar perf when using the default gcc7. However, with newer compiler and use of LSE, the graviton2 would provide higher performance : https://t.co/x9OgFqiPPy — NB (@N_B__N_B) March 9, 2021 First, the…

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